A film for replacing paint coatings is effective for improving the working environment because there are no VOCs (volatile organic compounds) and no spray mist. Furthermore, a film for replacing chrome plating is required in order to eliminate harmful chrome plating processes. A vacuum pressure forming method and a vacuum forming method have become common as methods used for these decorative films and sheets. In order to cover completely a deep drawn three-dimensional shaped object, these molding methods must be used, and a decorative film or sheet cannot be applied to this type of three-dimensional shaped object using conventional manual operations.
A polyolefin is lightweight, inexpensive, and safe, and therefore is most desirable as a resin for automotive components. However, polyolefin resin, and particularly polypropylene resin is said to be a poorly adhering material, and applying paint, metal, a film or the like is difficult.
Japanese PCT Patent Application Publication No. H2-503077 discloses a method for painting a plastic external vehicle panel of an automobile with a paint coat suitable for automotive external applications. The method comprises the step of applying a synthetic resinous material onto a surface of a soft casting sheet (42) in the shape of a thin-film, and drying a transparent coat on the casting sheet. The surface of the sheet has regular reflectivity for transferring a sufficient gloss level to the surface of the dried transparent coat for automotive external applications. The method also includes forming a color coating (46) of a colored synthetic resinous material, which is dried and then bonded to the transparent coat. The dried transparent coat and colored coating are transferred to a semihardened backing sheet (72) made of a synthetic resinous material to form a composite paint coat (44) bonded on the surface of the backing sheet. The transparent coat forms an outer surface on the transferred paint coat, the colored coating is bonded between the transparent coat and the backing sheet, and the outer surface of the transparent coat essentially maintains the gloss that is transferred from the casting sheet to the transparent coat. The backing sheet and the composite paint coat are thermally formed thereon to form a three-dimensionally shaped preliminarily formed laminate (116). The preliminarily formed laminate is placed in a mold, and a synthetic resinous substrate (118) is formed on the preliminarily formed laminate to form an automobile body exterior panel (130) with a finished automotive exterior paint coat. The transparent coat contains a material that essentially maintains the gloss level during the thermal molding process. The backing sheet has sufficient thickness and sufficient stretch to absorb defects that are present in the substrate, and maintains gloss essentially without defects on the surface of the transparent coat after the laminate is bonded to the substrate. The finished composite paint coat provides sufficient appearance and durability for use as an automotive exterior paint coat.
Japanese Patent No. 3851523 discloses a metal gloss sheet for three-dimensional molding that comprises a transparent thermoplastic resin film, a metal layer, an adhesive layer, and a thermoplastic resin film in order. The transparent thermoplastic resin film is composed of a polyester polymer compound with a benzene ring and a cyclohexane ring in the main chain, or a polyester polymer compound with a benzene ring and a naphthalene ring in the main chain.
Japanese Unexamined Patent Application Publication No. 2006-341388 discloses a method of forming a laminate sheet for thermal molding. In that method a laminate sheet for thermal molding having 1) a thermoplastic resin film layer, 2) a decorative layer with a metal vapor deposition layer or a highly volatile ink layer with metallic gloss and containing metal thin film pieces and a binder resin, and 3) a supporting base resin layer is molded at a molding temperature between (T1−20)° C. and (T2+35)° C. T1 is a temperature equal to the higher of either the softening temperature of the thermoplastic resin film layer or the softening temperature of the supporting substrate resin layer, and T2 is a temperature equal to the lower of either the softening temperature of the thermoplastic resin film or the softening temperature of the supporting substrate resin layer.